Host/client system having a scalable serial bus interface

ABSTRACT

According to one exemplary embodiment, a host/client system includes a host module, which includes a CPU coupled to a system bridge. The host/client system further includes at least one client having an integrated interface, where the integrated interface is coupled to the system bridge through a scalable serial bus. The system bridge and the integrated interface enable high bandwidth communication between the CPU and the at least one client through the scalable serial bus, thereby allowing control of bus width between the host module and the client.

1. TECHNICAL FIELD

The present invention is generally in the field of electronic circuits.More particularly, the present invention is in the field of businterface design.

2. BACKGROUND

Modern embedded systems, such as mobile phones and other portableelectronic devices, typically include a host CPU which communicates withvarious clients, such as volatile random access memory devices andnonvolatile random access memory devices, through conventionalmulti-drop bus interfaces. Such clients typically require many addressand control lines, thus requiring wide buses between the host CPU andthe clients, and may each require different interface and controlcircuitry.

As such embedded systems are continuously miniaturized to meet consumerdemand, however, the available space on the circuit boards used thereinas well as the cost to provide pins for the address, control and datalines on the device packages is becoming critically limited. As a resultof such space limitations, it has become difficult to enhance theperformance of the clients without further widening the already widebuses between the host CPU and the clients. Moreover, an increase in buswidth would require an increase in the pin counts of the host CPU andclients, thereby increasing costs. In addition, enhancing theperformance of the clients by increasing data transfer rates between thehost and the clients has also become difficult since the operationfrequencies of conventional multi-drop bus interfaces are rapidlyapproaching their physical limits.

SUMMARY OF THE INVENTION

The present invention is directed to a host/client system having ascalable serial bus interface. The invention addresses and resolves theneed in the art for a scalable serial bus interface which increasesperformance of a client while allowing control of bus width.

According to one exemplary embodiment, a host/client system includes ahost module, which includes a CPU coupled to a system bridge. Thehost/client system further includes at least one client having anintegrated interface, where the integrated interface is coupled to thesystem bridge through a scalable serial bus. The at least one client canbe, for example, a NOR type memory device, a NAND type memory device, ora volatile random access memory device. According to this exemplaryembodiment, the scalable serial bus is a time shared bus. According tothis exemplary embodiment, the integrated interface and the systembridge include a physical layer configured to receive and transmitelectronic signals using, for example, low voltage differentialsignaling. The integrated interface and the system bridge furtherinclude a control layer coupled to the physical layer. According to thisexemplary embodiment, the integrated interface and the system bridgeincludes an instruction layer.

In one embodiment, a number of clients having integrated interfaces canbe serially coupled to the integrated interface of the at least oneclient through the scalable serial bus, where the at least one clientand each of the number of clients are capable of communicating with eachother. The scalable serial bus enables scaling of the data transfer rateof the scalable serial bus, the number of channels on the scalableserial bus, and the bus width. Thus, the system bridge and theintegrated interface enable high bandwidth communication between the CPUand the at least one client through the scalable serial bus, therebyallowing control of bus width between the host module and the at leastone client. Other features and advantages of the present invention willbecome more readily apparent to those of ordinary skill in the art afterreviewing the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a host/client system having ascalable serial bus interface in accordance with one embodiment of thepresent invention.

FIG. 2 illustrates the details of the host/client system having ascalable serial bus interface in FIG. 1 in accordance with oneembodiment of the present invention.

FIG. 3 illustrates a block diagram of a host/client system having ascalable serial bus interface in accordance with one embodiment of thepresent invention.

FIG. 4 illustrates a block diagram of a host/client system having ascalable serial bus interface in accordance with one embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a host/client system having ascalable serial bus interface. The following description containsspecific information pertaining to the implementation of the presentinvention. One skilled in the art will recognize that the presentinvention may be implemented in a manner different from thatspecifically discussed in the present application. Moreover, some of thespecific details of the invention are not discussed in order not toobscure the invention.

The drawings in the present application and their accompanying detaileddescription are directed to merely exemplary embodiments of theinvention. To maintain brevity, other embodiments of the presentinvention are not specifically described in the present application andare not specifically illustrated by the present drawings.

FIG. 1 shows a block diagram of an exemplary host/client system having ascalable serial bus interface in accordance with one embodiment of thepresent invention. In FIG. 1, host/client system 100 includes hostmodule 102 and clients 112 and 114. Host module 102 includes CentralProcessing Unit (CPU) 106 coupled to system bridge 108 through systembus 110. As shown in FIG. 1, clients 112 and 114 have respectiveintegrated interfaces 116 and 118. For example, clients 112 and 114 canbe NOR type memory devices, NAND type memory devices, or dynamic randomaccess memory devices. As shown in FIG. 1, integrated interface 116 ofclient 112 is serially coupled to system bridge 108 through scalableserial bus 120, and integrated interface 118 of client 114 is seriallycoupled to integrated interface 116 of client 112 through scalableserial bus 120. In other embodiments, additional clients can be seriallycoupled between clients 112 and client 114. Therefore, in the presentembodiment, client 112 can represent the first client and client 114 canrepresent the nth client in a chain of serially coupled clients.

In host/client system 100 shown in FIG. 1, CPU 106 can communicate withsystem bridge 108 through system bus 110, which can be for example, anAdvanced High-performance Bus (AHB). System bridge 108 can communicatewith clients 112 and 114 through scalable serial bus 120. Scalableserial bus 120 can be, for example, a high bandwidth serial bus whichuses low voltage differential signaling (LVDS) or other relatedsignaling technology known in the art. As discussed below, the scalableserial bus 120 is a serial bus which can provide communication betweensystem bridge 108 and one or more clients (e.g., clients 112 and 114),scalable serial bus 120 can be used as a time shared bus where eachclient has access to the bus on a time-based access scheme (as opposedto a transaction-oriented bus where the bus is granted to a client untila particular transaction is completed resulting in less predictable busutilization). Accordingly, clients 112 and 114 in FIG. 1 will haveaccess to scalable serial bus 120 during particular timeslots by using,for example, an appropriate time division multiple access (TDMA) scheme.

Thus, system bridge 108, scalable serial bus 120 and interfaces 116 and118 in FIG. 1 enable high bandwidth serial communication between CPU 106in host module 102 and clients 112 and 114. As will be discussed,host/client system 100 in FIG. 1 allows CPU 106 to communicate with anyclient which is serially coupled to scalable serial bus 120. Eachintegrated interface (e.g., integrated interface 116) of each client(e.g., client 112) coupled to serial scalable bus 120 can interpretcommunications transmitted by CPU 106 to determine whether thecommunication is intended for its respective client, or for anotherclient. Communications intended for another client are sequentiallytransmitted from one neighboring client to the next until thecommunication reaches the intended client thus effectively implementinga routing protocol in a network, e.g. a chain as described in FIG. 1.

FIG. 2 shows host/client system 200, which illustrates the details ofhost/client system 100 shown in FIG. 1. Host/client system 200 in FIG. 2includes host module 202, clients 212 and 214, integrated interfaces 216and 218, and scalable serial bus 220 which correspond to host module102, clients 112 and 114, integrated interfaces 116 and 118, andscalable serial bus 120 in FIG. 1. Host module 202 in FIG. 2 includesCPU 206, system bridge 208, and system bus 210 which corresponds to CPU106, system bridge 108, and system bus 110 in FIG. 1.

As shown in FIG. 2, CPU 206 in host module 202 is coupled to and incommunication with system bridge 208 through system bus 210. Systembridge 208 includes physical layer 226, control layer 224, andinstruction layer 222. Physical layer 226 is coupled to control layer224, which is coupled to instruction layer 222. Physical layer 226 andcontrol layer 224 can each include, for example, control and payloadregisters (not shown in FIG. 2). As also shown in FIG. 2, system bridge208, integrated interface 216 of client 212, and integrated interface218 of client 214 are all serially coupled via scalable serial bus 220.As further shown in FIG. 2, host module 202 is in communication withclients 212 and 214, which can be situated, for example, in a separatemodule, such as client module 252. Integrated interface 216 in FIG. 2includes physical layers 228 a and 228 b, control layers 230 a and 230b, and data path control logic 232. Integrated interface 218 includesphysical layer 242, control layer 244, and data path control logic 246.

In client interface 216, physical layers 228 a and 228 b arerespectively coupled to control layers 230 a and 230 b. Control layers230 a and 230 b are each in communication with data path control logic232 via respective internal data paths 236 and 238. Data path controllogic 232 is coupled to instruction layer 256 and further coupled toclient 212 via client data path 240. Control layers 230 a and 230 b arealso in direct communication with each other via external data path 234.In integrated interface 218, physical layer 242 is coupled to controllayer 244. Control layer 244 is in communication with data path controllogic 246 via internal data path 248. Data path control logic 246 iscoupled to instruction layer 258 and further coupled to client 214 viaclient data path 254.

In host/client system 200 in FIG. 2, each physical layer (e.g., physicallayers 226, 228 a, 228 b, and 242) can perform electrical signalingfunctions, thereby allowing each physical layer to transmit and receivestreams of data (e.g., bitstreams) through scalable serial bus 220using, for example, low voltage differential signaling techniques. Eachcontrol layer (e.g., control layers 224, 230 a, 230 b, and 244) shown inFIG. 2 can decode incoming bitstreams to extract desired data and encodeoutgoing data into bitstreams for transmission over scalable serial bus220. Each control layer (e.g., control layers 224, 230 a, 230 b, and244) can also define the channels on scalable serial bus 220 and can mapoutgoing data into appropriate timeslots considering the number ofchannels and bit lanes available on scalable serial bus 220. Eachinstruction layer shown in FIG. 2 (e.g., instruction layers 222, 256,and 258) can initiate instructions based on incoming data received fromits associated control layer and can initiate outgoing instructions toits associated control layer 224 for encoding.

In an exemplary operation of host/client system 200, a command iscommunicated by CPU 206 to client 214 which, for example, can be a NORtype flash memory device. The command, which can be a memory read orwrite command, for example, is communicated to instruction layer 222which initiates the required instructions for execution of the commandand communicates these instructions to control layer 224. Theinstructions are then encoded by control layer 224 into a bitstream anda timeslot is specified for when transmission of the bit stream can takeplace. The bit stream is then provided to physical layer 226 andtransmitted through scalable serial bus 220 to the integrated interfaceof a neighboring client coupled to scalable serial bus 220 (e.g.,integrated interface 216).

The bit stream is then received by physical layer 228 a of integratedinterface 216 and is then communicated to control layer 230 a. Controllayer 230 a then determines whether the bit stream is intended forclient 212 or for another client. Since in the present example the bitstream is intended for client 214, the bit stream is transmitted bycontrol layer 230 a to control layer 230 b via external data path 234.The bit stream is then communicated to physical layer 228 b andtransmitted to physical layer 242 of integrated interface 218 viascalable serial bus 220. The bit stream is then communicated by physicallayer 242 to control layer 244, where it is decoded and communicated todata path control logic 246 through internal data path 248. The decodedbit stream is then communicated to instruction layer 258, where theappropriate instructions are initiated and provided to client 214through client data path 254.

Host/client system 200 in FIG. 2 also allows communication betweenclients that are serially coupled to scalable serial bus 220 throughtheir respective integrated interfaces. For example, client 214 cancommunicate data via data path 254 to data path control logic 246. Thedata can then be communicated via internal data path 248 to controllayer 244 and thus further communicated to physical layer 242 fortransmission to physical layer 228 b via scalable serial bus 220. Oncereceived by physical layer 228 b, the data can be communicated tocontrol layer 230 b and further communicated to data path control logic232 via internal data path 238. As mentioned above, each physical layer,control layer, and instruction layer, might include a control registerwhich can be configured to ensure proper switching between the datapaths, such as external data path 234 and internal data path 238. Thedata can then be communicated from data path control logic 232 to client212 via client data path 240.

FIG. 3 shows a block diagram of an exemplary host/client system inaccordance with one embodiment of the present invention. In FIG. 3,host/client system 300 includes host module 302 and clients 312 and 314.Host module 302 includes Central Processing Unit (CPU) 306 which iscoupled to and in communication with system bridge 308 through systembus 310. As shown in FIG. 3, clients 312 and 314 have respectiveintegrated interfaces 316 and 318. For example, clients 312 and 314 canbe NOR type memory devices, NAND type memory devices, or dynamic randomaccess memory devices.

As shown in FIG. 3, integrated interface 316 of client 312 is coupled tosystem bridge 308 through scalable serial bus 320 a, and interface 318of client 314 is coupled to system bridge 308 through scalable serialbus 320 b. In other embodiments, additional clients can be coupled tosystem bridge 308 through additional scalable serial buses. For example,system bride 308 can include a physical layer, a control layer, and aninstruction layer in a configuration similar to system bridge 208 inFIG. 2 and integrated interfaces 316 and 318 can each include aconfiguration of physical layers, control layers, instruction layers,and data path control logic blocks similar to the integrated interfacesdiscussed above, such as integrated interface 216. Thus, in the presentembodiment, each client (e.g., client 314) can communicate with CPU 306through system bridge 308 via its integrated interface (e.g., interface318) and scalable serial bus (e.g., scalable serial bus 320 b).

FIG. 4 shows a block diagram of an exemplary host/client system inaccordance with one embodiment of the present invention. In FIG. 4,host/client system 400 includes host module 402, client controller 418,and clients 412 and 414. Host module 402 includes Central ProcessingUnit (CPU) 406 coupled to system bridge 408 through system bus 410. Forexample, clients 412 and 414 can be NOR type memory devices, NAND typememory devices, or dynamic random access memory devices.

As shown in FIG. 4, client controller 418 is coupled to and incommunication with system bridge 408 through scalable serial bus 420.Clients 412 and 414 are coupled to client controller 418 through datapaths 422 and 424, respectively. In other embodiments, additionalclients can be coupled to client controller 418. For example, systembridge 408 and client controller 418 can include physical layers, acontrol layers, and instruction layers in a configuration similar tosystem bridge 208 in FIG. 2. For example, client controller 418 can be avideo module, a graphics module, or an encryption module. Clientcontroller 418 in FIG. 4 can include logic which can interpret commandscommunicated to a client (e.g., client 412) by CPU 406 to provide theclient with the proper signals (e.g., control signals) for execution ofthe commands. Thus, the embodiment of the invention shown in FIG. 4allows one or more clients to communicate with a CPU over a scalableserial bus using a client controller which can be adapted to interpretcommands transmitted and received between the CPU and each client.Accordingly, clients 412 and 414 in FIG. 4, which can be conventionalmemory devices that do not include integrated interfaces, can becontrolled through client controller 418 and thus interface with systembridge 408 without requiring modifications.

In other embodiments, a client with an integrated interface can becoupled to system bridge 408 through scalable serial bus 420. Clientcontroller 418 can then be coupled to the integrated interface of theclient to properly control other clients without integrated interfacesas described above. In addition, client controller 418 can implementsecurity features so as to allow the CPU to authenticate conventionalclients which do not include integrated interfaces.

The present invention, as shown in the embodiments in FIGS. 1 through 4,illustrates an exemplary host/client system where a CPU in a host modulecan communicate with one or more clients through a scalable serial bus.As discussed above, the scalable serial bus can provide high bandwidthcommunication between the CPU and the client and therefore, and canprovide higher data transfer rates than conventional multi-drop businterfaces by adjusting the bus frequency which is enabled bylow-voltage differential signaling I/Os. As such, the performance ofeach client can be increased without having to increase the bus widthbetween the host module and the clients, thereby allowing control of thebus width. Thus, since the present invention can actually increaseclient performance using fewer bus lines than conventional multi-dropbus interfaces, the respective pin counts of the host module and theclients can be advantageously reduced. Accordingly, the presentinvention can provide significant cost savings and facilitateroutability of bus lines between a host module and one or more clients.

Therefore, the present invention can also provide substantial designflexibility by allowing the scalable serial bus to scale in terms ofdata transfer rate, number of available channels, and bus width. Forexample, if a design incorporating the embodiment in FIG. 1 requiresmany clients, then latencies typically created by a long chain ofserially coupled Clients can be reduced by using additional scalableserial buses as shown in the embodiment of FIG. 3. Furthermore, thepresent invention can be conveniently integrated for use withconventional clients, e.g., conventional memory devices which do notinclude integrated interfaces, by using a client controller as shown inthe embodiment in FIG. 4.

As can be appreciated in the art, the present invention, for example theembodiment shown in FIG. 1 as host/client system 100, can be utilized ina variety of electronic modules, devices or electronic systems, forexample, a wired or wireless communications device, a cell phone, aswitching device, a router, a repeater, a codec, a LAN, a WLAN, aBluetooth enabled device, a digital camera, a digital audio playerand/or recorder, a digital video player and/or recorder, a computer, amonitor, a television set, a satellite set top box, a cable modem, adigital automotive control system, a digitally-controlled homeappliance, a printer, a copier, a digital audio or video receiver, an RFtransceiver, a personal digital assistant (PDA), a digital game playingdevice, a digital testing and/or measuring equipment, digital avionicsequipment, or a digitally-controlled medical equipment, or in any otherkind of module utilized in modern electronics applications.

From the above description of the invention it is manifest that varioustechniques can be used for implementing the concepts of the presentinvention without departing from its scope. Moreover, while theinvention has been described with specific reference to certainembodiments, a person of ordinary skill in the art would appreciate thatchanges can be made in form and detail without departing from the spiritand the scope of the invention. Thus, the described embodiments are tobe considered in all respects as illustrative and not restrictive. Itshould also be understood that the invention is not limited to theparticular embodiments described herein but is capable of manyrearrangements, modifications, and substitutions without departing fromthe scope of the invention.

Thus, a host/client system having a scalable serial bus interface hasbeen described.

The invention claimed is:
 1. A host/client system comprising: a systembridge; a host module including a CPU coupled to the system bridge; ascalable serial bus coupled to the system bridge; and first and secondclients, each having an integrated interface, the second client beingcoupled to the first client via the scalable serial bus and the firstclient being coupled to the system bridge via the scalable serial bus;wherein the integrated interface of the first client is configured to:receive a communication from the CPU over the scalable serial bus,determine whether the communication is intended for the first client,and, if so, to send the communication to an instruction layer of thefirst client, and determine whether the communication is intended forthe second client and, if so, to send the communication to the secondclient via the scalable serial bus.
 2. The host/client system of claim1, wherein the integrated interface of at least one of the first andsecond clients and the system bridge each include a physical layerconfigured to receive and transmit electronic signals using low voltagedifferential signaling.
 3. The host/client system of claim 2, whereinthe integrated interface of the at least one of the first and secondclients and the system bridge each include a control layer coupled tothe physical layer.
 4. The host/client system of claim 1, wherein theintegrated interface of the second client and the system bridge eachfurther comprise an instruction layer.
 5. The host/client system ofclaim 1, wherein at least one of the first and second clients a NOR typememory device, a NAND type memory device, or a dynamic random accessmemory device.
 6. The host/client system of claim 1, wherein the systemis utilized in an electronic device selected from a wired communicationsdevice, a wireless communications device, a cell phone, a switchingdevice, a router, a repeater, a codec, a LAN, a WLAN, a Bluetoothenabled device, a digital camera, a digital audio player and/orrecorder, a digital video player and/or recorder, a computer, a monitor,a television set, a satellite set top box, a cable modem, a digitalautomotive control system, a digitally-controlled home appliance, aprinter, a copier, a digital audio or video receiver, an RF transceiver,a personal digital assistant (PDA), a digital game playing device, adigital testing and/or measuring equipment, digital avionics equipment,or a digitally-controlled medical equipment.
 7. The host/client systemof claim 1, wherein the scalable serial bus is a time shared bus.
 8. Thehost/client system of claim 1, wherein the first and second clients areconfigured to communicate with each other using the scalable serial bus.9. The host/client system of claim 1, wherein the integrated interfaceof the first client is further configured to define channels on thescalable serial bus for the communication and to map the communicationto one or more timeslots for transmission on the scalable serial bus.